Medium Effect and Thermodynamic Studies for the Proton−Ligand and Metal−Ligand Formation Constants of the Ternary Systems MII+ Adenosine-5‘-triphosphate (ATP) + Asparagine

2001 ◽  
Vol 46 (2) ◽  
pp. 267-275 ◽  
Author(s):  
Ahmed A. A. Boraei ◽  
Fouad Taha ◽  
Ali H. Mohamed ◽  
Said A. Ibrahim
Keyword(s):  
Ternary Systems ◽  
Formation Constants ◽  
Medium Effect ◽  
Thermodynamic Studies ◽  
Metal Ligand

Thermodynamics of metal-ligand bond formation. XXIII. Lewis acidity of mercury(II) thiocyanate

1976 ◽  
Vol 29 (11) ◽  
pp. 2405 ◽  
Author(s):  
Y Farhangi ◽  
DP Graddon
Keyword(s):  
Bond Formation ◽  
Formation Constants ◽  
Adduct Formation ◽  
Lewis Acidity ◽  
Acetonitrile Solution ◽  
Enthalpies Of Formation ◽  
Dilute Solution ◽  
Lewis Bases ◽  
Metal Ligand ◽  
Ligand Bond

Thermodynamic data are reported for the reaction of Lewis bases with mercury(11) thiocyanate in acetonitrile solution. Pyridine, 4-methylpyridine and tetrahydrothiophen form 1 : 1 adducts with adduct formation constants and enthalpies of formation comparable to those with mercury(11) iodide. 1,l0-Phenanthroline, 2,2'-bipyridine and N,N,N',N?-tetramethylethane-1,2-diamine form chelate 1 : 1 adducts, but with enthalpies of formation little larger than that with pyridine. The phosphines, PPh3 and Pbu3, form 1 : 1 and 1 : 2 adducts of much greater stability, though the enthalpies of formation of these adducts are also similar to that with pyridine; Hg(SCN)2PBu3 is dimeric in dilute solution.

Complex formation of Tb3+ with glycolate, D-gluconate and α-isosaccharinate in neutral aqueous perchlorate solutions

2003 ◽  
Vol 91 (10) ◽  
Author(s):  
K. P. Zhernosekov ◽  
E. Mauerhofer ◽  
G. Getahun ◽  
Peter Warwick ◽  
Frank Rösch
Keyword(s):  
Complex Formation ◽  
Formation Constants ◽  
Carrier Free ◽  
Metal Ligand

SummaryAn electromigration technique was used for measurements of metal-ligand formation constants of non-carrier-free

Studies of reagents for spectrophotometric measurement of ionic magnesium

1977 ◽  
Vol 55 (22) ◽  
pp. 3909-3914 ◽  
Author(s):  
Dennis G. McMinn ◽  
Byron Kratochvil
Keyword(s):  
Complex Formation ◽  
Dissociation Constants ◽  
Formation Constants ◽  
Acid Dissociation ◽  
Disulfonic Acid ◽  
Acid Dissociation Constants ◽  
Spectrophotometric Measurement ◽  
Ph Range ◽  
Metal Ligand ◽  
The Ideal

Four mono-azo aryl dyes having the o-carboxy-o′-hydroxy functionality were investigated as reagents for the measurement of ionic Mg2+ in solutions containing complexing ligands. 2-(2′-Carboxyl-1′-benzeneazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid came closest to the ideal of having absorbance unaffected by pH over the pH range of interest and of differentiating between Ca2+ and Mg2+ complex formation. Ligand acid dissociation constants and formation constants for the metal–ligand complexes were measured.

Capillary electrophoresis facilitates determination of metal complex stoichiometry by Job’s method of continuous variation

2013 ◽  
Vol 10 (5) ◽  
pp. 409 ◽  
Author(s):  
Nathan E. Boland ◽  
Alan T. Stone
Keyword(s):  
Capillary Electrophoresis ◽  
Chelating Agent ◽  
Formation Constants ◽  
Continuous Variation ◽  
Spectroscopic Characteristics ◽  
Peak Areas ◽  
Method Of Continuous Variation ◽  
Job's Method ◽  
Metal Ligand

Environmental context Knowledge of metal-chelating agent speciation is integral to our ability to predict and interpret the behaviour of synthetic chelating agents in the environment. Capillary electrophoresis can be used to separate metal–ligand complexes with similar spectroscopic characteristics but different stoichiometries, thereby providing insight into metal–ligand speciation that is not possible by any other technique. Here, we demonstrate the utility of capillary electrophoresis for the determination of metal–ligand stoichiometries and evaluate its limitations. Abstract Job’s method of continuous variation is a traditional method used to determine the stoichiometry of metal–ligand complexes. The method is often applied to whole-sample absorbance measurements but its utility is limited when two or more complexes are present at significant concentrations and have similar absorption spectra. Here we employ capillary electrophoresis (CE), which separates complexes on the basis of charge and hydrodynamic radii, to extend the capabilities of Job’s method. Solutions containing nickel(II) and diethylenetriaminepentaacetic acid (DTPA) yield three CE peaks. Job’s method plot maxima, based on areas for each of the three CE peaks, coincide with nickel(II)-to-DTPA ratios of 1 : 1 and 1 : 2, which correspond to two complexes previously identified using whole-sample measurements, plus a ratio of 3 : 2, which corresponds to a previously unreported complex. We demonstrate how CE peak areas and electromigration times can be used to determine complex stoichiometries and formation constants. We discuss the strengths and weaknesses of Job’s Method coupled with CE and implications for speciation determination in environmentally relevant systems.

scholarly journals Thermodynamics of metal-ligand bond formation. VIII. Pyridine adducts of zinc(II) β-diketonates

1973 ◽  
Vol 26 (11) ◽  
pp. 2537 ◽  
Author(s):  
DR Dakternieks ◽  
DP Graddon
Keyword(s):  
Benzene Solution ◽  
Equilibrium Constants ◽  
Bond Formation ◽  
Formation Constants ◽  
Adduct Formation ◽  
Enthalpies Of Formation ◽  
Calorimetric Titration ◽  
Experimental Conditions ◽  
Metal Ligand ◽  
Ligand Bond

Equilibrium constants and enthalpies in benzene solution are reported for the formation of 1 : 1-adducts of pyridine with four zinc(II) complexes of β-diketones, determined by calorimetric titration. Adduct formation constants at 30�C fall in the range 300-2000 and enthalpies of formation lie between -15 and - 34 kJ mol-1. Though the enthalpies of formation differ little from those of corresponding copper(II) complexes, the adducts are about a hundred times more stable. The pyridine adduct of bis(2,2,6,6-tetramethylheptane-3,5-dionato)zinc(II) is entropy-stabilized relative to those of other complexes. No evidence was obtained for the addition of a second molecule of pyridine under the experimental conditions used.

Discrete fragment model for apparent formation constants of actinide ions with humic substances

2015 ◽  
Vol 103 (6) ◽  
Author(s):  
Takayuki Sasaki ◽  
Hatsumi Yoshida ◽  
Shunsuke Aoyama ◽  
Taishi Kobayashi ◽  
Ikuji Takagi ◽  
...  
Keyword(s):  
Humic Substances ◽  
Binding Sites ◽  
Formation Constant ◽  
Fulvic Acids ◽  
Formation Constants ◽  
Humic And Fulvic Acids ◽  
Wide Range ◽  
Parameter Values ◽  
Actinide Ions ◽  
Metal Ligand

AbstractA semi-empirical thermodynamic model was applied to estimate the apparent formation constants of actinide ions, i.e., Th(IV), Pu(IV) and Np(V), with humic substances (HSs), including humic and fulvic acids, over a wide range of solution conditions, i.e., pH, ionic strength, and HS and metal concentrations. The hypothetical HSs consist of humic and fulvic acids with nine types of simple organic ligands, which include aromatic and aliphatic carboxyl groups and phenol groups, as binding sites. The abundance of each binding site in the hypothetical HSs was determined via a fitting analysis using an acid-dissociation dataset for several HSs. To determine the apparent formation constant of a given metal ion with HSs, 54 specific binding sites were considered, including nine monodentate sites (1:1 metal/ligand complexes) and 45 bidentate sites (1:2 metal/ligand complexes). The formation constant of each monodentate binding was determined from the experimental data, while those of the bidentate bindings were determined by considering two monodentate bindings and the chelating effect, for which one of the adjustable parameters was introduced in the model. Introduction of the other parameter, which is related to the fraction of monodentate to bidentate sites (i.e., the heterogeneity), afforded the parameter values with good correlation with the apparent formation constant data. The present model with adjusted parameter values well reproduced the experimental apparent complex formation constants for actinide ion interaction with HSs in a wide range of solution conditions except for those obtained at trace concentrations.

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